U.S. patent application number 13/929647 was filed with the patent office on 2014-06-05 for apparatus for the automated handling of workpieces.
The applicant listed for this patent is Liebherr-Verzahntechnik GmbH. Invention is credited to David Haenschke, Thomas Mattern, Alois Mundt, Bernhard Riedmiller.
Application Number | 20140154036 13/929647 |
Document ID | / |
Family ID | 48792923 |
Filed Date | 2014-06-05 |
United States Patent
Application |
20140154036 |
Kind Code |
A1 |
Mattern; Thomas ; et
al. |
June 5, 2014 |
Apparatus for the automated handling of workpieces
Abstract
An apparatus for the automated handling of workpieces comprising
at least one gripper for picking the workpiece; a control for
controlling the at least one gripper and an intermediate station
for placing the workpiece, with the apparatus being configured such
that the workpiece is placed in a defined position and/or defined
orientation on the intermediate station and is picked up again with
a changed orientation and/or with greater accuracy.
Inventors: |
Mattern; Thomas; (Rieden,
DE) ; Haenschke; David; (Altusried, DE) ;
Riedmiller; Bernhard; (Wertach, DE) ; Mundt;
Alois; (Kempten, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Liebherr-Verzahntechnik GmbH |
Kempten |
|
DE |
|
|
Family ID: |
48792923 |
Appl. No.: |
13/929647 |
Filed: |
June 27, 2013 |
Current U.S.
Class: |
414/729 ;
414/783; 414/816 |
Current CPC
Class: |
B25J 9/0084 20130101;
B65G 47/1478 20130101; B25J 11/00 20130101; B25J 19/023 20130101;
G05B 2219/39508 20130101; B65G 2203/041 20130101; B25J 9/0096
20130101; B25J 9/1612 20130101 |
Class at
Publication: |
414/729 ;
414/783; 414/816 |
International
Class: |
B25J 11/00 20060101
B25J011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 29, 2012 |
DE |
10 2012 013 022.8 |
Jun 18, 2013 |
EP |
13 003 103.2 |
Claims
1. An apparatus for automated handling of workpieces comprising at
least one gripper for picking up the workpieces, a control for
controlling the at least one gripper, and an intermediate station
for placing down the workpieces, wherein the apparatus is
configured such that the workpieces are placed on the intermediate
station in a defined position and/or in a defined orientation and
are picked up again with a changed orientation and/or with a
greater accuracy.
2. The apparatus in accordance with claim 1, wherein the at least
one gripper for placing the workpieces and/or for the repeat
picking up of the workpieces is a mechanical, pneumatic, or
magnetic gripper.
3. The apparatus in accordance with claim 2, wherein the same
gripper is used for placing down and for the repeat picking up of
the workpieces; or wherein two separate grippers are used for
placing down and for the repeat picking up of the workpieces.
4. The apparatus in accordance with claim 1, wherein the
intermediate station has at least one receiver in which the
workpieces can be placed in a defined position and/or orientation,
with the at least one receiver advantageously being specifically
adapted to the workpieces.
5. The apparatus in accordance with claim 4, wherein the at least
one receiver allows a picking up of a workpiece with at least two
different orientations of the gripper toward the workpiece, for
example a gripping from two sides, with the workpiece
advantageously being placed down gripped from a first side for
changing the orientation of the workpiece and being picked up again
gripped from the other side.
6. The apparatus in accordance with claim 4, wherein the
intermediate station and/or the at least one receiver has a
compensation apparatus which allows an inaccurate placing down.
7. The apparatus in accordance with claim 6 comprising a
positioning arrangement which arranges and/or fixes the workpieces
and/or the compensation apparatus in a predefined position for the
more exact picking up of the workpieces.
8. The apparatus in accordance with claim 5 comprising a travel
arrangement by which the workpieces and/or the at least one
receiver is traveled on the intermediate station; wherein abutments
and/or fixing regions are advantageously provided against which the
workpiece and/or the at least one receiver are moved for fixing;
and/or wherein the at least one receiver can be traveled from a
placing position into a removal position, with the receiver
advantageously having a compensation apparatus which is movable in
the placing position, which allows an inaccurate placing and which
can be fixed by traveling into the removal position, with a
plurality of receivers advantageously being arranged next to one
another.
9. The apparatus in accordance with claim 8 comprising a plurality
of receivers for receiving workpieces, wherein the plurality of
receivers advantageously serve as a storage apparatus and/or as a
transport apparatus.
10. The apparatus in accordance with claim 4 comprising a
functional region and/or a functional arrangement which serve, for
example, a pretreatment, recognition and/or marking of the
workpieces, in particular a demagnetization station, wherein the at
least one receiver can advantageously be traveled from a placing
position into a removal position, with the workpieces running
through the functional arrangement on the traveling of the at least
one receiver.
11. The apparatus in accordance with claim 2 for automated removal
of workpieces arranged in a container comprising an object
recognition device for detecting the workpieces and a first gripper
for picking and removing the workpieces from the container; and a
control for evaluating data of the object recognition device and
for controlling the first gripper; and comprising a first
intermediate station on which the first gripper places the
workpieces after the removal from the container; and comprising a
positioning apparatus which positions the workpieces more
accurately starting from the intermediate station and/or
singularizes them; wherein the positioning apparatus advantageously
places the workpieces on a second intermediate station in a defined
position and/or in a defined orientation and the workpieces are
picked up from the second intermediate station again with a changed
orientation and/or with greater accuracy.
12. An intermediate station for the apparatus in accordance with
claim 2, with the at least one receiver allowing a picking up of
workpieces from two sides and/or having a compensation apparatus
which allows an inaccurate placing.
13. A method for the automated handling of workpieces on an
apparatus for automated handling of workpieces comprising at least
one gripper for picking up the workpieces, a control for
controlling the at least one gripper, and an intermediate station
for placing down the workpieces,wherein the apparatus is configured
such that the workpieces are placed on the intermediate station in
a defined position and/or in a defined orientation and are picked
up again with a changed orientation and/or with a greater accuracy,
wherein workpieces are placed on an intermediate station in a
defined position and/or in a defined orientation and are picked up
again with a changed orientation and/or with a greater
accuracy.
14. The method in accordance with claim 13, wherein the workpieces
are placed on the intermediate station with a certain permitted
inaccuracy and are fixed in a specific position thereon for the
more accurate picking up; and/or wherein the workpieces are placed
down gripped from a first side for changing the orientation at the
gripper and are picked up again gripped from the other side.
15. (canceled)
Description
[0001] The present invention relates to an apparatus for the
automated handling of workpieces having at least one gripper for
picking the workpiece, a control for controlling the at least one
gripper and an intermediate station for placing down the
workpiece.
[0002] The apparatus can in this respect in particular be used with
such automated handling procedures in which randomly arranged
workpieces are detected by an object recognition device and a
control of the gripper takes place using the data of the object
recognition device to place the workpieces on the intermediate
station. The apparatus in accordance with the invention can,
however, also be used with other automated handling procedures.
[0003] It is the object of the present invention in this respect to
provide an apparatus which allows a reliable and flexible handling
of workpieces with process security.
[0004] This object is solved in accordance with the invention by an
apparatus in accordance with claim 1. Advantageous embodiments of
the present invention form the subject of the dependent claims.
[0005] The present invention shows an apparatus for the automated
handling of workpieces having at least one gripper for picking the
workpiece, a control for controlling the at least one gripper and
an intermediate station for placing down the workpiece. In
accordance with the invention, the apparatus is configured in this
respect such that the workpiece is placed on the intermediate
station in a defined position and/or in a defined orientation and
is picked up again with a changed orientation and/or with a greater
accuracy.
[0006] The present invention thus allows a workpiece which was
already able to be picked or placed with a certain accuracy to be
picked up again in a first embodiment variant with greater accuracy
due to placing on the intermediate station and a repeat picking
[0007] Alternatively or additionally, the placing of the workpiece
can serve to pick up the workpiece again with a changed orientation
toward a gripper. This is in particular important when a workpiece
can be picked up with different orientations toward the gripper,
but can only be arranged at a target receiver with a defined
orientation toward the gripper. In this case, the intermediate
station in accordance with the invention can be used to achieve
this orientation toward the gripper by placing and picking up again
with a changed orientation.
[0008] The present invention can in this respect in particular be
used as a part of an apparatus which serves the automated
arrangement of the workpieces at a target receiver, wherein the at
least one gripper is controlled so that the workpiece picked up
from the intermediate station is arranged with the desired
orientation and/or accuracy at the target receiver.
[0009] The target receiver can in this respect be a receiver of a
transport apparatus which transports the workpiece to a machining
station. The workpiece can, however, also be arranged directly at a
machining station, starting from the intermediate station, with the
intermediate station in this case also being able to take over a
transport function.
[0010] The at least one gripper to place down the workpiece and/or
to pick up the workpiece again is particularly preferably a
mechanical gripper. Such a mechanical gripper allows good accuracy
in the placing down and picking up of the workpiece. Alternatively,
however, a pneumatic and/or magnetic gripper can also be used.
[0011] In a first embodiment variant of the present invention, the
same gripper can in this respect be used both for placing down the
workpiece and for a repeat pick-up of the workpiece.
[0012] Alternatively, two separate grippers can be used, i.e. a
first gripper for placing the workpiece down and a second gripper
for picking it up again. Advantageously, in this case, the two
grippers can be moved separately, in particular by two separate
gripping arms at which the grippers are each arranged.
Alternatively, the two grippers can, however, also be arranged at a
common gripping arm.
[0013] In a preferred embodiment of the present invention, the
intermediate station includes at least one receiver in which the
workpiece can be placed down in a defined position and/or
orientation. Such a receiver thus enables a placing down in
accordance with the invention of the workpiece in a defined
position and/or orientation on the intermediate station.
Advantageously, the receiver is in this respect specifically
matched to the workpiece and takes up the workpiece in this respect
in a defined position and/or orientation.
[0014] Advantageously, the receiver in this respect allows a
picking of the workpiece with at least two different orientations
of the gripper toward the workpiece, for example a picking from two
sides. This in particular allows the orientation of the gripper
relative to the workpiece to be varied by placing down and picking
up again. In this respect, a change in the orientation of the
workpiece can in particular take place in that it is placed down
while gripped from one side and is picked up again while gripped
from the other side.
[0015] In a further preferred embodiment of the present invention,
the intermediate station and/or the receiver comprises a
compensation apparatus which allows an inaccurate placing down.
Provision can in particular be made in this respect that the
receiver is arranged at the intermediate station with a certain
play and thus yields correspondingly on an inexact placing of the
workpiece.
[0016] The placing down in a defined position in the sense of the
present invention thus also comprises a placing down in a defined
region which is defined, for example, by the movability of the
receiver or of the compensation apparatus.
[0017] Further advantageously, a positioning arrangement can be
provided which arranges and/or fixes the workpiece and/or the
compensation apparatus in a predefined position and thus allows a
more accurate picking of the workpiece.
[0018] Furthermore, the intermediate station can have a travel
arrangement by which the workpiece and/or the receiver is traveled
on the intermediate station. Advantageously, in this respect,
abutments and/or fixing regions are provided toward which the
workpiece and/or the receiver is traveled for fixing and/or
positioning. This in particular allows the accurate positioning of
a workpiece placed on the intermediate station with a inaccuracy
permitted despite the defined placing down.
[0019] Provision can furthermore be made that the receiver can be
traveled from a placing position into a removal position. This on
the one hand makes it possible that the placing down of a workpiece
takes place in a different position than the picking up so that
they impede one another less, in particular on the use of two
grippers.
[0020] Provision can furthermore be made that the receiver has a
compensation apparatus which is movable in the placing down
position, which allows a non-accurate placing down and can be fixed
and/or positioned by traveling into the removal position. The
workpiece can hereby be picked more accurately in the removal
position.
[0021] In a particularly advantageous embodiment of the present
invention, a plurality of receivers are arranged next to one
another. The receivers are in this respect in particular arranged
next to one another transversely to the respective traveling
direction.
[0022] The apparatus can in this respect furthermore have a
plurality of receivers for receiving workpieces. The receivers can
in this respect in particular serve as a storage apparatus so that
the intermediate station in accordance with the invention serves as
a store in addition to the repeat picking with greater accuracy
and/or changed orientation. Alternatively or additionally, the
receivers can also serve the further transport of the received
workpieces. The receivers are, for example, arranged on a transport
belt for this purpose.
[0023] Furthermore, an apparatus in accordance with the present
invention can have a functional region and/or a functional
arrangement which, for example, serves the pretreatment, the
recognition and/or the marking of the workpieces. It can in this
respect be a demagnetization station, for example. It is equally
conceivable to identify or to detect and/or to mark the workpieces
by reading a label and/or by printing with a label.
[0024] Provision can therefore in particular be made that the
receiver can be traveled from a placing position into a removal
position, with the workpieces running through the functional
arrangement on the traveling of the receiver. The receiver can in
this respect in particular be movable in the placing position, as
already presented above, and can be fixable on the traveling into
the removal position. A dual function of the intermediate station
hereby results.
[0025] The intermediate station in accordance with the present
invention can in this respect be configured such that the picking
back up of the workpiece from the intermediate station takes place
without a detection of the position of the workpiece. The
intermediate station can in particular be configured such that the
workpiece is arranged so exactly at the intermediate station in its
removal position that a detection of the workpiece is not necessary
for the correct controlling of the gripper with which the workpiece
is removed.
[0026] The workpiece is, in contrast, advantageously detected by an
object recognition device in order hereby to control the gripper
which picks up the workpiece and places it on the intermediation
station in accordance with the invention. In this respect, randomly
arranged workpieces can in particular be detected by an object
recognition device, wherein an identification of the workpieces and
a selection of a workpiece to be picked take place by evaluation of
the data of the object recognition device, with reference to which
data a track planning takes place and the gripper is
controlled.
[0027] The apparatus in accordance with the invention can in this
respect be a part of a total apparatus for the automated removal of
workpieces arranged in a container, which apparatus has a first
object recognition device for detecting the workpieces and a first
gripper for picking and removing the workpieces from a container as
well as a control for evaluating the data of the first object
recognition device, for track planning and for controlling the
first gripper. The control can in this respect in particular
comprise an evaluation device for evaluating the data, a track
planning module for track planning and a control unit for
controlling the gripper. Furthermore, this apparatus can comprise a
first intermediate station onto which the first gripper places the
workpiece after the removal from the container and can comprise a
positioning apparatus which positions the workpieces more
accurately and/or singularizes them, starting from the intermediate
station.
[0028] The apparatus can in this respect in particular serve the
removal of workpieces randomly arranged in the container since the
position of the workpieces can be determined by a suitable object
recognition device and therefore does not have to be known in
advance. The apparatus can naturally, however, also be used when
the workpieces are already present with a certain order in the
container.
[0029] The first intermediate station can in this respect be an
intermediate station in accordance with the present invention.
[0030] The intermediate station in accordance with the invention,
on which the workpiece is placed in a defined position and/or
orientation, is, however, particularly preferably a second
intermediate station. Provision can in this respect in particular
be made that the positioning apparatus places the workpiece on the
second intermediate station in accordance with the present
invention in a defined position and/or in a defined orientation and
the workpiece is again picked up from the second intermediate
station with a changed orientation and/or with greater
accuracy.
[0031] Provision can be made in this case that the placing of the
workpieces on the first intermediate station takes place randomly.
The workpieces can in this respect in particular be dropped onto a
placing region of the first intermediate station from a certain
height. In this respect, a slanted plane is, for example, provided
onto which the workpieces are dropped and from which they slide to
a transport device.
[0032] Provision can in this respect furthermore be made that a
repeat detection of the workpieces takes place on the intermediate
station by a second object recognition device for the corresponding
control of a gripper of the positioning apparatus.
[0033] In accordance with this invention, in this respect, a
magnetic and/or pneumatic gripper, in particular a magnetic
gripper, can be used as the first gripper with which the workpieces
are removed from the container. This is in particular possible when
the workpieces do not have to be placed on the first intermediate
station with a defined position.
[0034] In contrast, a mechanical gripper is advantageously used as
the positioning apparatus or as the gripper with which the
workpieces are placed on the second intermediate station in
accordance with the invention since it allows a more accurate
placing down. Alternatively, however, a pneumatic and/or magnetic
gripper can also be used here.
[0035] In accordance with the invention, the first gripper and/or
the second gripper can be moved via automatically controlled
adjustment axes of a gripping arm. In a first embodiment variant,
the first gripper and the second gripper can in this respect be
arranged at a common gripping arm and can be moved via it. The
first and second grippers are, however, preferably arranged at
separate gripping arms and can thus be moved independently of one
another.
[0036] The present invention furthermore comprises an intermediate
station for an apparatus such as was presented above.
[0037] The present invention furthermore comprises an intermediate
station having a receiver in which the workpieces can be placed
down in a defined position and/or orientation. Advantageously, the
receiver allows a picking of the workpiece with at least two
different orientations of the gripper toward the workpiece, for
example a picking from two sides. Alternatively or additionally,
the receiver can have a compensation apparatus which allows an
inaccurate placing down.
[0038] The intermediate station is in this respect advantageously
configured as has already been presented in more detail above with
respect to the apparatus in accordance with the invention.
Provision can in this respect in particular be made that the
compensation apparatus can be fixed and/or positioned. Provision
can furthermore be made that the receiver of the intermediate
station is arranged in a displaceable manner, with the compensation
apparatus advantageously being fixed and/or positioned by a
displacement of the receiver.
[0039] Furthermore, a plurality of receivers can be provided for
receiving workpieces. The receivers can in particular serve as a
storage apparatus in this respect. Alternatively or additionally,
the receivers can also serve the further transport of the received
workpieces. The receivers are, for example, arranged on a transport
belt for this purpose.
[0040] The present invention furthermore comprises a method for the
automated handling of workpieces, wherein a workpiece is placed on
an intermediate station in a defined position and/or in a defined
orientation and is picked up again with a changed orientation
and/or with greater accuracy. The workpiece is in this respect in
particular placed on the intermediate station in a corresponding
receiver.
[0041] Provision is in this respect advantageously made in
accordance with the invention that the workpiece is placed on the
intermediate station with a certain permitted inaccuracy and is
positioned and/or fixed on it in a specific position for a more
accurate picking Provision can alternatively or additionally be
made that the workpiece is placed down while gripped from a first
side for changing the orientation at the gripper and is picked up
again while gripped from the other side.
[0042] The method in this respect advantageously takes place as was
already presented above with respect to the apparatus. The method
in accordance with the invention can in this respect in particular
take place while using an apparatus in accordance with the
invention.
[0043] The present invention furthermore comprises a computer
program for the carrying out of a method as was presented above. In
this respect, the computer program in particular comprises commands
which implement the method in accordance with the invention on an
apparatus for the automated handling of workpieces. The computer
program in accordance with the invention can in this respect in
particular be used for implementing a control for an apparatus in
accordance with the invention as was presented above.
[0044] All the steps in the handling of the workpieces
advantageously take place by the method in accordance with the
invention and/or by the apparatus in accordance with the invention
in a fully automated manner and without a user intervention being
necessary.
[0045] The subject of the present invention will now be described
in more detail with reference to embodiments and to drawings.
There are shown:
[0046] FIG. 1 a flowchart of a detection in accordance with the
invention of workpieces and of a corresponding control of a
gripper;
[0047] FIG. 2 a first embodiment of an apparatus which can be used
for moving a gripper in accordance with the invention;
[0048] FIG. 3 a second embodiment of an apparatus which can be used
for moving a gripper in accordance with the invention;
[0049] FIG. 4 a first embodiment of an apparatus in accordance with
the invention for the automated removal of workpieces randomly
arranged in a container;
[0050] FIG. 4a an alternative embodiment of a transport path as can
be used on the intermediate station in the embodiment shown in FIG.
4;
[0051] FIG. 5 a first gripper of the embodiment shown in FIG.
4;
[0052] FIG. 6 a detailed view of the gripper shown in FIG. 5;
[0053] FIG. 7 a second gripper of the embodiment shown in FIG.
4;
[0054] FIG. 8 an embodiment of a travelable object recognition
device as can be used in the embodiment shown in FIG. 4;
[0055] FIG. 9 the travelable object recognition device shown in
FIG. 8 in a side view;
[0056] FIG. 10 a second embodiment of an apparatus in accordance
with the invention for the automated removal of workpieces randomly
arranged in a container in which an embodiment of an intermediate
station in accordance with the invention having a revolving
transport path is used;
[0057] FIG. 11 a third embodiment of an apparatus for the automated
removal of workpieces randomly arranged in a container, which is
based on the embodiment shown in FIG. 4 and which furthermore
comprises an embodiment of a second intermediate station on which
workpieces can be placed in at least one receiver;
[0058] FIG. 12 the embodiment of a second intermediate station as
is used in the apparatus in accordance with FIG. 11 in a detailed
view;
[0059] FIG. 13 a fourth embodiment of an apparatus in accordance
with the invention for the automated removal of workpieces randomly
arranged in a container, which is based on the embodiment shown in
FIG. 4 and which furthermore comprises a second embodiment of a
second intermediate station on which workpieces can be placed in a
receiver;
[0060] FIG. 14 a fifth embodiment of an apparatus in accordance
with the invention for the automated removal of workpieces randomly
arranged in a container which is based on the embodiment shown in
FIG. 4 and which furthermore comprises a measuring device by means
of which a measurement of the picking accuracy is possible;
[0061] FIG. 15 a detailed representation of an embodiment of a
measuring device in accordance with the invention in which the
picking accuracy can be measured;
[0062] FIG. 16 an embodiment of a gripper in accordance with the
invention with a stabilizer element;
[0063] FIG. 17 a sectional view through the embodiment of a gripper
shown in FIG. 16;
[0064] FIG. 18 a first embodiment of a compensation unit in
accordance with the invention;
[0065] FIG. 19 a sectional view through the compensation unit shown
in FIG. 18;
[0066] FIG. 20 a second embodiment of a compensation unit in
accordance with the invention,
[0067] FIG. 21 a front view of and a sectional view through the
compensation unit shown in FIG. 20;
[0068] FIG. 22 a side view of the compensation unit shown in FIG.
20;
[0069] FIG. 23 a flowchart of a method for detecting workpieces in
accordance with the present invention;
[0070] FIG. 24 a flowchart of a method for the picking in
accordance with the invention of workpieces from a container;
and
[0071] FIG. 25 a flowchart of a method for the picking in
accordance with the invention of workpieces from an intermediate
station.
[0072] Embodiments of apparatus for the automated handling of
workpieces will be presented in the following in which the present
invention is used.
[0073] The individual embodiments in this respect in particular
serve the fully automatic singularization and/or positioning of
workpieces. In this respect, any desired elements can be handled as
workpieces, in particular also asymmetrical workpieces beside
workpieces with one or more planes or symmetry or axes of symmetry.
Furthermore, workpieces can be handled in this respect which only
have one gripping point or workpieces having a plurality of
gripping points. The apparatus in accordance with the invention can
in this respect in particular be used for handling metal
workpieces. The workpieces can, however, naturally comprise any
desired materials and in particular also plastic. The workpieces
can furthermore also comprise a plurality of materials, for example
a combination of plastic parts and metal parts.
[0074] In part in this respect, a gripper for picking the workpiece
is combined with an object recognition device for detecting the
workpieces so that the gripper can be controlled using the data
determined by the object recognition device. Such apparatus in
particular serve the automated handling of randomly arranged
workpieces.
[0075] The object recognition device for detecting the workpieces
can in this respect comprise any desired sensor whose data allow an
object recognition of the workpieces. A laser scanner can in
particular be used in this respect. Alternatively or additionally,
the object recognition device can comprise one or more cameras. The
object recognition device in this respect preferably allows a 3D
object recognition. Alternatively, however, a 2D or 2.5D object
recognition is conceivable.
[0076] FIG. 1 shows the typical routine on the detection of
randomly arranged workpieces and the corresponding control of a
gripper. In step 1, a measurement is carried out by the object
recognition device by which data is obtained. These data are
processed in a step 2 to allow an identification of the individual
workpieces in a step 3. Optionally, the object recognition device
can, however, also work using already known positional data of the
workpieces.
[0077] In step 4, a workpiece which can be picked by the gripper is
selected from the identified workpieces. In step 5, the track for
the gripper or for the gripping arm moving the gripper is
calculated using the positional data of the selected workpiece. In
step 6, this track is then checked for possible collisions with
interfering edges to prevent collisions. If a collision-free track
is found, it is used in step 7 for controlling the gripper, i.e.
for traveling the gripper into a picking position toward the
selected workpiece.
[0078] Such a method can in this respect always be used when a
detection of the workpieces and a corresponding control of a
gripper take place in accordance with the present invention.
[0079] The apparatus and methods in accordance with the invention
can in this respect in particular serve the handling of randomly
arranged workpieces since the position of the workpieces can be
determined by a suitable object recognition device and therefore
does not have to be known in advance. The present invention can
naturally, however, also be used when the workpieces are already
arranged in a certain order.
[0080] Any desired apparatus having a plurality of axes of movement
can be used for moving the gripper and the gripper can be moved on
a defined track and can be traveled toward the workpiece to be
picked via the control of said axes of movement.
[0081] In FIG. 2, a first embodiment of such an apparatus for
moving a gripper is shown, with it being a multiaxial robot 10. It
is in this respect a six-axial robot in the embodiment. It
comprises a base 11 on which a pedestal 12 is arranged rotatably
about a vertical axis of rotation. A pivot arm is pivotably
arranged about a horizontal pivot axis at the pedestal 12. A rotary
arm 14 is arranged around a horizontal pivot axis at the pivot arm
13. The rotary arm 14 furthermore more has an axis of rotation
which allows a rotation about an axis of rotation arranged in
parallel with the rotary arm 14. A gripping arm 15 is arranged
around a pivot axis arranged perpendicular to the axis of rotation
of the rotary arm 14 at the rotary arm 14. The gripping arm has an
axis of rotation which stands perpendicular on the pivot axis. In
accordance with the invention, a gripper can be arranged at the
gripping arm and can thus be moved and pivoted in space via the
control of the axes of movement of the robot.
[0082] In FIG. 3, an alternative embodiment for an apparatus for
moving a gripper is shown which can be used in all embodiments of
the present invention instead of a robot. In this respect, it is a
surface portal which has three linear axes of movement and is
additionally equipped with a further axis of rotation. In this
respect, portal rails 21 are provided at which a portal bar 22 is
arranged in a linearly travelable manner. A slide 23 is likewise
arranged in a linearly travelable manner at the portal bar 22. An
arm is arranged travelable in the vertical direction at the slide
23. This arm is additionally equipped with an axis of rotation 25.
The arm can in this respect have a gripper in accordance with the
present invention at its lower end.
[0083] In FIG. 4, a first embodiment of an apparatus in accordance
with the invention for the automated removal of workpieces is shown
which combines an object recognition device 30 for detecting the
workpieces with a first gripper 34 for picking the workpieces to
remove the workpieces arranged randomly in a container from the
container using the first gripper 34. In this respect, the
workpieces are not arranged directly at a target receiver by the
first gripper 34, but are rather placed down in a random
arrangement on the intermediate station from where they are
positioned more accurately via a second gripper 41.
[0084] The embodiment in this respect has a receiver 31 for a
container, not shown, with workpieces randomly arranged therein.
Furthermore, a channeling in and channeling out device 32 can be
provided for such containers. The object recognition device 30 for
detecting the workpieces in the container is provided above the
container, not shown. Its data are evaluated as initially described
such that the workpieces are gripped in the container via the first
gripper 34 and can be removed from it. The first gripper 34 is in
this respect moved via a robot 33 in the embodiment. Alternatively,
a surface portion can also be used here.
[0085] In the embodiment, a magnetic gripper is used as the first
gripper 34 since such a magnetic gripper makes less high demands on
the delivery accuracy of the gripper to the workpiece and is
therefore better suited actually to empty containers 100% having
workpieces which are arranged chaotically in them and which
moreover can be stacked over one another in random positions, as is
possible in accordance with the embodiment of the present
invention.
[0086] It is in particular possible with a magnetic gripper also to
pick workpieces having a non-ideal picking position. In this
respect, a certain offset can in particular be present between the
gripping surface of the magnetic gripper and a main surface of the
workpiece. In addition, a picking is optionally also possible when
the magnetic gripper only engages at the highest point of a
workpiece. If the control can therefore not identify any workpiece
which can be ideally picked using the data of the object
recognition device, that is with which an ideal superimposition of
the gripping surface and a main surface of the workpiece is
present, a picking with an offset or a picking at a highest point
can alternatively be made use of Such a picking can equally be made
use of when another picking strategy did not result in the picking
up of a part.
[0087] A pneumatic gripper could also be used alternatively to the
magnetic gripper 34. It is equally conceivable to replace the
magnetic gripper 34 shown in the embodiment in accordance with FIG.
4 by a mechanical gripper if the workpieces are shaped such that
they can also be reliably picked in the container by a mechanical
gripper.
[0088] The first object recognition device 30 can furthermore be
used to recognize workpieces which arrived erroneously in the
container. If a workpiece is detected in this respect which does
not satisfy the required workpiece criteria and is therefore not to
be positioned at a target receiver, this can be separated out, for
example in that the workpiece is picked and is placed in a
corresponding container.
[0089] In accordance with the embodiment, the workpieces are not
arranged at a target receiver by the first gripper, but are rather
placed on an intermediate station from where they are picked up
again by the second gripper 41 and are then positioned more
accurately. The placing down of the workpieces on the intermediate
station can take place in a random arrangement in this respect. The
workpieces can in this respect in particular be dropped by the
gripper 34 from a predefined height onto a placing region 35 of the
intermediate station. The placing region 35 is in this respect
configured as a sloping plane from which the workpieces slide to a
further transport zone.
[0090] The placing region 35 can have one or more height sensors
which determine the height of a workpiece arranged at the gripper
34 above the placing region. In this respect, in particular a light
barrier arrangement 37 can be provided which is arranged to the
side of the slanted plane 35. If in this respect a workpiece
arranged at the gripper 34 arrives in the region of the light
barrier arrangement, this means that the workpiece is arranged at a
certain height above the slanted plane 35. The gripper 34 thereupon
drops the workpiece. This procedure has the advantage that the
position of the workpieces at the gripper 34 does not have to be
exactly known. Collisions of the gripper with the placing region
are nevertheless prevented. Provision can in this respect in
particular be made that the gripper 34 first moves in a horizontal
direction into a position above the placing region 35 after the
picking up of a workpiece from the container and then lowers it so
far until the vertical sensor responds.
[0091] The intermediate station furthermore has a transport belt 38
which transports the workpieces from the placement region 35 on to
a removal region 44.
[0092] The workpieces in this respect slide from the slanted plane
onto the transport belt 38, with the slanted plan 35 being able to
be bounded by lateral abutment regions 36 which narrow the slanted
plane downwardly so that the workpieces are directed to a defined
further transport region of the transport belt.
[0093] This further transport region is advantageously equipped
with an occupation sensor 39. It can in this respect in particular
be a light barrier arrangement which determines the height of the
workpieces placed on the transport belt. If a plurality of
workpieces are stacked above one another, the occupation sensor
responds. In this case, the further loading of the intermediation
station by the first gripper 34 is stopped until the occupation
sensor again signals a sufficiently free further transport
region.
[0094] The workpieces are transported on the transport belt 38 into
the removal region 44 and are there picked by the second gripper 41
to be positioned more accurately or to be singularized. In this
respect, a second object recognition device 42 is provided which
detects the workpieces in the removal region, with the second
gripper 41 being controlled with reference to the data of the
second object recognition device. A robot 40 is in turn provided
for moving the second gripper 41. Alternatively, a surface portal
could also be made use of here.
[0095] The second object recognition device 42 is necessary for
picking the workpieces since they lie in a random arrangement on
the intermediate station or on the transport belt. The picking
situation on the intermediate station is, however, substantially
simpler than with the container since the workpieces are all
arranged in the same plane, i.e. on the transport belt, at least in
the vertical direction. In addition, the workpieces are already
presingularized and so can be picked more easily. In addition, the
workpieces have a defined distance from the object recognition
device 42 so that it works more accurately.
[0096] The second object recognition device 42 can furthermore be
used to recognize workpieces which arrived erroneously on the
intermediate station. If in this respect a workpiece is detected on
the intermediate station which does not satisfy the required
workpiece criteria and is therefore not to be positioned at a
target receiver, it can be separated out, for example in that the
workpiece is picked and is placed into a corresponding container or
in that it is not picked and transported via the transport belt
further into a container.
[0097] Provision can be made in this respect that the second object
recognition device allows a more accurate detection of the
workpieces than the first object recognition device so that
incorrect workpieces are reliably recognized on the intermediate
station.
[0098] In accordance with the invention, a mechanical gripper 41
can therefore be used as the second gripper which admittedly makes
higher demands on the delivery of the gripper to the workpiece, but
also allows a substantially more exact picking and positioning of
the workpieces. In the embodiment, the mechanical gripper is a
finger gripper, in particular a two-finger gripper such as will be
presented later.
[0099] The control of the transport belt is in this respect in
communication with the object recognition device 42 and the control
of the gripper 41. In this respect, the transport belt stops in
each case when a detection of the workpieces and the following
picking of a workpiece by the gripper 41 takes place. If, in
contrast, there are no longer any workpieces in the removal region
44, the transport belt is moved on until workpieces are again
located in the removal region 44. For this purpose, a light barrier
arranged laterally at the transport belt in the removal region can
optionally also be used for this purpose in addition to the data of
the object recognition device.
[0100] The side walls of the transport belt 38 can be chamfered, as
can be recognized in FIG. 4. It is hereby prevented that workpieces
remain in unfavorable positions directly at the side wall which do
not allow any picking
[0101] Provision can furthermore be made that a reorientation
apparatus is provided transversely over the transport belt 38 which
flips over unfavorably arranged workpieces and thus brings them
into a better position for picking by the second gripper 41. For
example, a flap, not shown, or an abutment bar can be provided for
this purpose which are arranged above the transport belt 38. Such a
reorientation apparatus can in particular be arranged between the
further transport belt 38 and the removal region 44 of the
transport belt.
[0102] In this respect, provision can be made in accordance with
the invention that workpieces which cannot be picked at all by the
gripper 41 fall into a collection container arranged at the end of
the transport path 38. Alternatively, a peripheral transport belt
43 can be provided such as will be described in more detail
later.
[0103] Alternatively to the transport belt which is used as the
transport device in FIG. 4, a number of other alternatives are
available for the configuration of the transport device. The basic
idea of the intermediate station is in this respect the design with
a loading side and an unloading side, a transport device between
the two sides and a further object recognition device over the
removal side. The transport from one side to the other side can
take place as follows, for example:
[0104] Driven transport device: [0105] Linearly working transport
device [0106] Pusher, shuttle, slide, in particular driven by
linear drives such as a pneumatic cylinder [0107] Transport
belt
[0108] Circular [0109] Round, segment table, circular store [0110]
Loop or circular belt
[0111] A plurality of planes above one another [0112] From bottom
to top [0113] From top to bottom
[0114] Non-driven transport devices: [0115] Slanted plane on which
the workpieces slide down Combination of the above-named driven
transport devices and/or non-driven transport devices.
[0116] The position of the workpiece is preferably changed during
the transport to increase the removal accuracy (place down
inaccurately, remove accurately). This can be achieved by end
abutments, guide rails with chamfer, spring mechanisms, etc. The
intermediate station can furthermore also be used as a transfer
picking site.
[0117] In this respect an alternative configuration of the
transport device on the intermediate station is shown in FIG. 4a
such as can be used in the embodiment shown in FIG. 4. In the upper
region, the first gripper 33 is shown which picks the workpieces
from the container and places them in the placing region 38 on the
intermediate station. In the lower region, the second gripper 40 is
shown which removes the workpieces in the removal region 44. The
second object recognition device 42 is furthermore shown which is
arranged in the region of the removal region 44.
[0118] In this respect a first transport plate 301 is provided as
the transport device which can be traveled from the placing region
38 to the removal region 44 and back via a linear drive 302 such as
a pneumatic cylinder. In addition, a second transport plate 303 is
provided which can likewise be traveled from the placing region 38
to the removal region 44 and back via the linear drive 304. The two
transport plates and linear drives can be configured identically in
this respect. The two transport devices can furthermore be arranged
in parallel with one another. An empty transport plate is always
available for loading or a filled transport plate for unloading
through the embodiment with two transport plates so that the system
can work without waiting times.
[0119] In FIGS. 5 and 6, an embodiment of a first gripper in
accordance with the invention is now shown again such as can in
particular be used for picking up the workpieces from a container.
It is a magnetic gripper 34 in this respect. In this respect, a
magnetic gripping surface 47 is provided at the lower side of the
gripper. The magnetic gripper 34 in this respect has an
electromagnet which generates a magnetic force on the magnetic
gripping surface 47 for holding magnetizable objects.
[0120] The gripper in accordance with the invention is arranged
cropped at the end member of the gripping arm, for example at the
end member of the gripping arm of a robot 33. In this respect, a
central axis of the gripper 34 or of the magnetic gripping surface
47 is arranged offset by a spacing 48 from an axis of rotation of
the last pivot joint of the gripping arm. For this purpose, a
cropped arm 45 is provided which connects the magnetic gripper 34
to the gripping arm. It is possible by the cropped configuration of
the gripper also to use it directly next to a side wall of the
container in the interior of the container for picking workpieces.
It is thus in particular avoided that interfering edges further up
at the gripping arm prevent a moving of the magnetic gripper
directly to a wall region of the container.
[0121] A compensation unit 46 such as will be described in more
detail in the following can furthermore be provided. This prevents
an overload of the gripping arm from taking place on a collision of
the gripper 34 with interfering edges or with workpieces. In
addition, it is prevented that a safety deactivation of the robot
is activated which would only be able to be bridged manually.
[0122] In FIG. 7, an embodiment of the second gripper 41 is shown
which is likewise arranged at a gripping arm of a robot 40. In the
embodiment, a two-finger gripper having fingers 50 which can be
traveled in a linear manner is used as the gripper in this respect.
The fingers can in this respect move into cut-outs of the
correspondingly shaped workpieces and can grip the workpiece by
moving apart or moving together. With differently shaped
workpieces, other mechanical grippers can naturally also be used,
in particular three-finger or multifinger grippers or bar grippers.
A compensation unit 49 which protects the robot arm from overload
on collisions is also provided in the embodiment shown in FIG.
7.
[0123] FIG. 8 shows an embodiment of an object recognition device
for detecting workpieces which can be traveled from a position of
rest into a measuring position and back by a travel
arrangement.
[0124] The object recognition device shown in FIG. 8 can in this
respect in particular be used in the embodiment shown in FIG. 4 as
an object recognition device 30 for detecting the workpieces in a
container. The second object recognition device 42 used in the
embodiment shown in FIG. 4 for detecting the workpieces on the
intermediate station is in contrast rigid in the embodiment.
Alternatively, however, this object recognition device 42 could
also have a travel arrangement to be able to travel from a position
of rest into a measuring position and back.
[0125] The object recognition device shown in FIG. 8 has a sensor
30 which detects the workpieces. The sensor 30 is arranged at a
sensor arm 52 which is arranged in a travelable manner at a guide
rail 54. The guide rail 54 is in turn arranged at a mounting bar 51
in order to thus be able to mount the fastening pieces 55 on a
pedestal. The exact arrangement of the two pedestal columns can be
recognized in FIG. 4.
[0126] In the embodiment shown in FIG. 4, the object recognition
device is in this respect arranged on pedestal columns such that
the containers can be led between the pedestal columns on the
channeling into a removal position.
[0127] As can be recognized in FIGS. 8 and 9, the sensor 30 can be
traveled along the guide rail 54 by moving the sensor arm 52. In
the embodiment, the object recognition device is structured in this
respect such that the sensor 30 can be traveled in a horizontal
direction.
[0128] In the position of rest, the object recognition device is
located outside a collision region with the first gripper 34 so
that it has free access to the container. The sensor 30 is then
traveled over the container by traveling out the sensor arm 52 into
the measuring position in which the detection of the workpieces
takes place for detecting the workpieces in the container. In its
measuring position, the sensor 30 is located approximately
centrally above the container. After the measurement, the sensor is
again moved back into the position of rest in which it is arranged
outside the base surface of the container.
[0129] In this respect, the movements of the object recognition
device and of the removal gripper 35 are synchronized with one
another so that the detection of the workpieces in the container
always takes place when the gripper 34 places a workpiece on the
intermediate station. The object recognition device is then
traveled back into the position of rest so that the gripper 34 can
remove a new workpiece from the container. In the following placing
of the workpiece on the intermediate station, a measurement in turn
takes place.
[0130] A similar procedure would in this respect also be
conceivable with the second object recognition device 42 and the
second gripper 41.
[0131] Alternatively or additionally, the object recognition device
could also be traveled in the vertical direction. On the one hand,
such a vertical travel capability could be used in the same way as
the horizontal travel capability to move the sensor out of a
collision region with the gripper when the latter picks up a
workpiece and to move it closer toward the workpieces again to
carry out a detection. In addition, it would be conceivable to
track the object recognition device in a vertical direction with an
emptying filling level of the container so that the object
recognition device is always arranged in an unchanging distance
region from the workpieces arranged the highest in the container in
the measurement. A constant detection quality can hereby be
achieved.
[0132] In the embodiment, a laser scanner can be used as a sensor
of the object recognition device. The scanner can in this respect
transmit a plurality of laser beams at small intervals so that a
fan of laser beams is created. The fan formed by the laser beams is
then pivoted over the detection region by pivoting the sensor,
whereby a spatial detection of the detection region takes place.
Geometrical data are created in this respect by distance
measurement using the laser beams.
[0133] An arrangement of the sensor approximately centrally above
the container in this respect has the advantage that the side walls
of the container do not form shadows. The travel capability of the
sensor in this respect makes it possible to position the sensor in
the measuring position at a sufficiently small distance from the
workpieces to be measured and nevertheless not to come into
conflict with the gripper or with the gripper arm moving the
gripper. This is in particular of special importance when detecting
the workpieces in the container since the scanner has to be
positioned so low above the container, at least when it cannot be
traveled vertically, that it still detects workpieces with
sufficient accuracy with an almost emptied container.
[0134] In FIG. 10, a further embodiment of an apparatus in
accordance with the invention for the automated removal of
workpieces from a container is shown which is based on the
embodiment shown in FIG. 4 and in which the peripheral transport
path of the intermediate station is provided which is only
indicated schematically in FIG. 4. Except for the differently
configured intermediate station, all the components in this respect
correspond to the embodiment shown in FIG. 4 so that reference is
made to the description there with regard to the total design of
the apparatus.
[0135] The intermediate station also has a first transport belt 38
in the embodiment shown in FIG. 10, which transport belt transports
workpieces placed in a placing region 35 to a removal region 44.
The workpieces are there detected by the object recognition device
42 and are picked and removed by the gripper 41 which is moved by
the gripping arm 40.
[0136] In accordance with the invention, the intermediate station
shown in FIG. 10 is now equipped with a return path 60 which allows
workpieces not removed in the removal region 44 to run around. The
return path 60 is in this respect likewise a transport belt which
is arranged next to the first transport belt 38 and is moved in the
opposite direction. The return path 60 in this respect ensures that
workpieces not removed in the removal region 44 are transported
back and again arrive on the first transport belt 38 so that they
again move into the removal region 44 where they can again be
detected and picked.
[0137] If therefore a workpieces on its first detection lies at
such a position in the removal region 44 that it cannot be picked
or can only be picked with difficulty, the control can dispense
with a picking attempt and can allow the workpiece to run around.
The circulation path is in this respect designed such that the
workpiece is very highly likely to arrive in the removal region 44
in a different position on the next circulation so that there is a
high probability that the workpiece lies in a position which can be
picked more easily on the second attempt. Workpieces with which an
unsuccessful picking attempt was made can also be treated in the
same way.
[0138] The removal region could also be arranged in the region of
the return path in the embodiment shown in FIG. 10 without the
function of the intermediate station changing.
[0139] Since the workpieces lie randomly arranged on the transport
belts 38 and 60, the probability is very high that they change
their position on the circulation. This can be assisted by further
measures in accordance with the invention. An abutment 61 is thus
provided, for example, which extends obliquely over the first
transport belt 38 and forces the workpieces from the first
transport belt 38 onto the return path 60. In the same way, an
abutment 62 is provided at the end of the return path 60 which
conveys the workpiece back onto the first transport path 38 again.
In this respect, a positional change of the workpieces is effected
solely by the contact with the abutments and the forcing onto the
respective other belt.
[0140] Provision can furthermore be made that the workpieces run
through a vertical difference during the circulation. A slanted
plane or an edge having a vertical difference can in particular be
provided in this respect over which the workpieces are forced. A
position change is also hereby effected. At the same time,
workpieces caught up with one another can optionally be separated
from one another.
[0141] In this respect, a slanted plane which the workpieces slide
down is advantageously provided in the transition region between
the first transport belt 38 and the return path 60. The first
transport path 38 in this respect advantageously extends in the
vertical direction, whereas the return path 60 is arranged
obliquely so that a vertical difference results in at least one of
the two end regions of the two transport paths.
[0142] To prevent parts which cannot be picked from remaining on
the circulation path for an unlimited time, a separation mode can
be provided in which the circulation is ended under certain
conditions and the workpieces are emptied into a collection
container 63. The abutment 61 can in particular be moved for this
purpose such that the workpieces are transported via the first
transport path 38 up to its end and into the container 63 placed
there.
[0143] In this respect, in particular a separation mode can be
provided in which no new workpieces are placed onto the
intermediate station by the first gripper. At least one picking
attempt then takes place with all the workplaces located on the
intermediate station. In this respect, a plurality of circulations
can optionally also be carried out. The workpieces then remaining
on the intermediate station can then be emptied into the container
63. It is thereupon in turn possible to switch into the normal
mode.
[0144] The separation mode can furthermore be used to separate out
workpieces which erroneously arrived on the intermediate station.
The separation mode can thus be activated when a workpiece was
detected on the intermediate station which does not satisfy the
demanded workpiece criteria and is therefore not to be positioned
at a target receiver.
[0145] In the embodiment of an intermediate station shown in FIG.
10, the reorientation device 64 is also shown which was already
described with regard to the embodiment in FIG. 4, but which was
not shown there. In this respect, it is a flap which is arranged
above the first transport belt 38 between the placing region and
the removal region. The flap 64 should in this respect in
particular flip over workpieces standing on their edge to make them
easier to pick.
[0146] In FIG. 11, a further embodiment of an apparatus in
accordance with the invention for the automated removal of
workpieces arranged in a container is shown. This embodiment is
also based on the embodiment shown in FIG. 4 so that reference is
first made to the description of the embodiment shown in FIG. 4
with respect to the configuration.
[0147] On the one hand, the channeling in and out for containers
with workpieces is shown which is only shown schematically in FIG.
4. They are put to one side and are moved from there in an
automated fashion into the removal region 31. The workpieces are
now removed after one another by the first gripper 34 until the
container is 100% empty. The emptied container is thereupon moved
to the channeling out path and is channeled out from there.
[0148] In this respect, a safety detection of the container
interior advantageously takes place again after the removal of the
last workpiece to ensure that actually no more workpieces remain in
the container. If therefore the control only identifies a single
workpiece on a detection procedure and if the gripper was
controlled accordingly to remove it, a further detection procedure
is nevertheless initiated. Only in this way can it be ensured that
the last detected workpiece was also actually removed.
[0149] Furthermore, the embodiment shown in FIG. 11 shows a second
intermediate station 65 on which the workpieces removed from the
first intermediate station by the gripper 41 are placed to be
picked again. The placing on the second intermediate station in
this respect takes place in a defined position, with the placing
serving to be able to pick more accurately on the picking up and/or
to be able to vary the orientation of the workpiece at the gripper.
The second intermediate station can furthermore also serve as a
buffer store.
[0150] An embodiment of such an intermediate station 65 is shown in
FIG. 12. The intermediate station has at least one receiver 67 for
the workpieces into which the workpiece can be placed in a defined
position and orientation. In the embodiment, in this respect, a
plurality of such receivers 67 are arranged next to one another so
that the intermediate station also serves as a buffer store.
[0151] The receivers 67 have a compensation apparatus 70 which also
allows a placing of the workpieces in the receiver 67 with a
certain positional offset in that the receiver is moved by the
contact with the workpiece to be placed down. For this purpose, the
receiver 67 has receiver steps 72 against which a badly positioned
workpiece first abuts and in so doing causes a movement of the
receiver by which the workpiece can be placed in the receiver.
[0152] The receiver 67 thus allows a placing of workpieces in a
defined positional region and thus in particular also allows the
placing of workpieces not exactly picked in a desired position.
[0153] The compensation unit 70 can be fixed on the intermediate
station so that the receiver and thus the workpiece is arranged in
a defined desired position for the removal. The removal of the
workpiece can hereby take place with a greater accuracy.
[0154] The receivers 67 are displaceable on rails 69 at the
intermediate station. In this respect, the receivers can be
displaced from a loading position, in which the compensation unit
allows a movement of the receivers 67, into a removal position in
which the compensation unit is fixed. Abutments 71 are provided for
this purpose into which the receiver 67 is traveled and which fix
the receiver in a defined position.
[0155] The placing and the removal of workpieces onto the second
intermediate station 65 in this respect in each case advantageously
takes place by mechanical grippers since they have a relatively
high picking accuracy by which the workpieces can be placed in a
defined manner in the receivers and can be picked up again with a
higher accuracy.
[0156] The picking of the workpieces on the second intermediate
station in this respect takes place without a previous detection of
the workpieces in that the grippers are traveled to the known
removal position of the receiver.
[0157] The receivers are furthermore designed so that the
workpieces can be picked from two different directions. In the
embodiment, the workpieces in this respect have cut-outs into which
the fingers of a finger gripper engage. The receivers are designed
in this respect such that the cut-outs are accessible from two
sides in the workpieces when a workpiece is arranged in the
receiver. The orientation of the workpiece at the gripper can
hereby be reversed in that the workpiece is picked from one side on
the placing down, but from the other side on the picking up.
[0158] In this respect, the placing down and the picking up can
take place by the same gripper. In the embodiment shown in FIG. 11,
however, two separate grippers are used.
[0159] In the embodiment of an apparatus in accordance with the
invention shown in FIG. 13, which is likewise based on the
embodiment shown in FIG. 4, a further embodiment for a second
intermediate station 73 is now shown. This intermediate station
also has at least one receiver 74 in which workpieces can be placed
down in a defined manner. The receiver is in this respect designed
in exactly the same way as the receivers shown in FIG. 12.
[0160] The intermediate station shown in FIG. 13 in this respect
has a transport belt by which the receiver 74, which is at least
movable to a certain extent on the transport belt, can be traveled
toward abutments to fix it in its position. A compensation unit is
also hereby provided which allows a placing down of the workpieces
in the receiver 74 with a certain offset and which nevertheless
moves the workpiece or the receiver for removal into a defined
position so that picking can again take place with higher accuracy.
Furthermore, picking can also take place here from both sides to
change the orientation of the workpiece at the gripper.
[0161] The intermediate station 73 shown in FIG. 13 is furthermore
equipped with a functional unit 75 which the workpieces run through
on the intermediate station. The functional unit is in this respect
a demagnetization station through which the workpieces are guided
on the intermediate station.
[0162] In the embodiment shown in FIG. 13, the same mechanical
gripper 41 is in this respect used both for placing the workpieces
on the intermediate station 73 and for removing the workpieces.
[0163] Furthermore, a determination of the picking accuracy can
take place with an apparatus for the automated handling of
workpieces in accordance with the present invention. It can in this
respect in particular be determined whether and/or how much the
position of a workpiece picked up at the gripper differs relative
to the gripper from a predefined desired picking position or from a
predefined desired picking position region. The process routing of
the handling is advantageously then controlled in dependence on the
result of such a picking accuracy determination.
[0164] In this respect, an embodiment of an apparatus in accordance
with the invention is shown in FIGS. 14 and 15 with which the
picking accuracy is determined by traveling the gripper with the
workpiece toward a separate measuring device 77. For this purpose,
the gripper 41 is traveled into a defined position before the
measuring device 77 when it has picked a workpiece 78. The
measuring device 77 then determines the position of the workpiece
78 and can thus determine the relative position between the
workpiece and the gripper from the known position of the gripper
and the position of the workpiece. A determination of the picking
accuracy or of the position of the workpiece at the gripper is
hereby possible.
[0165] In the embodiment, the separate measuring device 77 has
laser sensors 79 in this respect. In the embodiment, a three-point
measurement is carried out in this respect.
[0166] A determination of the picking accuracy can in particular be
of advantage with mechanical grippers since they admittedly allow a
relatively exact picking of the workpieces, but there are also
degrees of freedom on picking here. If it is a finger gripper or a
jaw gripper, the workpiece can usually be picked in different
positions at least with respect to the delivery direction of the
gripper to the workpiece. With the finger gripper, this relates to
the question how far the fingers engage into a corresponding
receiver at the workpiece or how far the fingers engage around the
workpiece.
[0167] In the embodiment of an apparatus in accordance with the
invention shown in FIG. 14 which is based on the embodiment shown
in FIG. 4, the picking accuracy of the gripper 41 which is used for
removing the workpieces from the first intermediate station is in
this respect determined. Alternatively, however, the picking
accuracy on the removal of a workpiece from a second intermediate
station could also be determined.
[0168] Alternatively to the separate measuring device which is
shown in FIGS. 14 and 15 and toward which the gripper can be
traveled, a sensor arranged at the gripper itself can also be used
for determining the picking accuracy. An embodiment for such a
sensor will be described in more detail in the following.
[0169] The result of the determination of the picking accuracy can
in this respect be used in different manners for controlling the
apparatus.
[0170] On the one hand, it is possible that a picking error on the
placing of the workpiece recognized in this determination is
compensated by a corresponding control of the griper or of the
gripping arm moving it. This substantially corresponds to a zero
point adjustment of the gripper on placing which changed in
dependence on a deviation of the workpiece from a desired picking
position.
[0171] It is furthermore conceivable that poorly picked workpieces
are placed down again to be picked again. Such a procedure can in
particular be sensible when the picking accuracy lies outside a
predefined permitted region.
[0172] In this respect, the workpiece can be placed back on the
transport belt on the picking from an intermediate station with a
transport belt such as is shown in FIG. 4 or 14, for example, when
the picking accuracy falls below certain criteria. In an
advantageous manner, the workpiece is in this respect placed onto
the transport belt in a position from where the workpiece again
arrives in the removal region. The workpiece is in this respect
advantageously again detected and then again picked using the data
determined from this. In this respect, the probability is high that
the workpiece can now be picked with sufficient accuracy.
[0173] In this respect, a combination of the two procedures is also
conceivable. If the accuracy therefore lies outside a permitted
region, the workpiece is placed back. Otherwise, the determined
deviation from a desired picking position on the placing down of
the workpiece is compensated by a corresponding movement.
[0174] In FIG. 16, an embodiment of a gripper in accordance with
the invention with a stabilizer element is shown. In the
embodiment, it is in this respect a mechanical gripper with which
the workpiece is picked. To prevent positional changes of the
workpiece at the gripper, while the gripper is moved, the
stabilizer element 80 is traveled toward the picked workpiece. The
stabilizer element 80 has a stabilizer plate at which contact
elements are provided for contacting the workpiece. The additional
contact points thus provide a positional fixing of the workpiece at
the gripper.
[0175] In the embodiment the gripper is configured as a two-finger
gripper having the two gripping fingers 50 which are introduced
into cut-outs of the workpieces for picking The two contact points
established by the two gripping fingers 50, however, do not fix the
workpiece in a clear position with respect to the gripper so that
only the further contact points of the stabilization element
establish a defined position of the workpiece at the gripper. The
contact points of the stabilizer element are in this respect
advantageously arranged remote from line connecting the two
gripping fingers 50 in this respect.
[0176] In the embodiment, the stabilizer element 80 is arranged in
the region of the two gripping fingers and is attached around it.
The stabilizer element could, however, also be arranged in any
other position at the gripper.
[0177] The design of the stabilizer element can again be recognized
in the sectional view shown in FIG. 17. In this respect, the
stabilizer plate 81 can be recognized at which, for example,
contact elements can be arranged in the region 82. The stabilizer
plate 81 surrounds the gripping finger 50 in this respect in the
form of a ring or of a horse-shoe in the embodiment.
[0178] The stabilizer plate 81 is arranged at a cylinder 83 by
which it can be traveled to the workpiece. The cylinder 83 is a
pneumatic cylinder. The stabilizer element can thus be traveled
toward the workpiece when pneumatic pressure is applied at the one
side of the cylinder or can be traveled in when pressure is applied
to the other side of the cylinder.
[0179] The end abutments 84 and 85 of the cylinder 83 are equipped
with sensors which recognize whether the stabilizer element is
located in one of its end abutment regions. A determination of the
picking accuracy is hereby possible since the moving-out distance
of the stabilizer element depends on the position of the picked
workpiece at the gripper.
[0180] If the stabilizer element is in this respect located in the
active state in one of its end abutment regions, an insufficient
picking accuracy is concluded since the gripper was then either
traveled too far into the workpiece or not far enough. A more
precise determination of the picking accuracy could naturally also
take place by a measurement of the push-out length of the cylinder
83.
[0181] Alternatively to the sensor arrangement integrated into the
stabilizer element 82 for determining the picking accuracy, a
separate sensor would also be conceivable which is arranged at the
gripper. For example, in this respect, a laser sensor could be used
which is arranged at the gripper to determine the picking
accuracy.
[0182] In FIG. 17, a compensation unit 49 can also be seen via
which the gripper is fastened to a gripping arm.
[0183] In FIGS. 18 and 19, a first embodiment of such a
compensation unit is shown in more detail. In this respect, a base
element 90 is provided at which a compensation plate 91 is
arranged. The compensation plate 91 is engaged around by holding
elements 92 of the base element 90. A spring arrangement 93 which
presses the compensation plate 91 toward the holding regions 92 is
arranged between the base element 90 and the compensation plate 91.
In the embodiment, in this respect, a plurality of coil springs are
provided which are arranged in corresponding spring sleeves.
However, any desired other embodiments of such a spring arrangement
are also conceivable.
[0184] The spring force of the spring arrangement is in this
respect selected such that the compensation plate 91 is held
rigidly at the base unit 90 in normal operation of the gripper.
Only in the case of a collision of the gripper or of the workpiece
arranged therein with an interfering edge or with another workpiece
does the spring arrangement 93 allow a relative movement between
the compensation plate 91 and the base element 90. The forces
exerted on the gripping arm are hereby limited. It can in
particular thus be prevented that the emergency stop of a robot
used for moving the gripper or of a surface portal engages.
[0185] The force of the spring arrangement 93 can in this respect
be set so that the compensation element can be adapted to the
corresponding purpose. The setting of the spring force can in this
respect in particular take place in that the gripper is moved
together with a picked up workpiece into a 90.degree. position to
the vertical so that the static load by the gripper and the
workpiece on the compensation unit is at a maximum. In this
position, the preload of the spring arrangement 93 is set so that
no deflection of the compensation unit takes place. It is hereby
ensured that no deflection of the compensation unit takes place
independently of the orientation of the gripper by the static
forces alone which are applied to the compensation unit by the
gripper and a picked up workpiece. Optionally, the preload of the
spring arrangement 93 can in this respect still be increased by a
certain value in order also to take account of dynamic loads, for
example on the acceleration of the gripper or of the gripper
arm.
[0186] The preload of the spring arrangement 93, however, has to be
selected so that the compensation unit triggers before the
emergency stop of the gripper arm engages.
[0187] The first embodiment of a compensation unit in accordance
with the invention can in this respect, for example, be used
together with a mechanical gripper. The first embodiment of a
compensation unit in accordance with the invention can in this
respect in particular be used for the second gripper which picks up
the workpieces from the intermediate station. Furthermore, the
first embodiment of the compensation unit in accordance with the
invention can also be used with the third gripper which picks up
the workpieces from the second intermediate station.
[0188] The first embodiment of the compensation unit in accordance
with the invention in this respect has a spherical operation and in
particular allows tilt compensation movements. The compensation
unit in this respect advantageously allows a maximum compensation
angle between 2.degree. and 10.degree., in particular between
4.degree. and 6.degree..
[0189] In this respect, guide elements are furthermore provided
which prevent a rotation of the compensation plate 91 with respect
to the base element 90. In the embodiment, guide pins engage for
this purpose laterally in corresponding cut-outs of the
compensation plate 91.
[0190] The compensation plate is in this respect round in the
embodiment and has rounded edges to allow a pivot movement around
any desired axes.
[0191] Contact sensors 94 are furthermore arranged in the region of
the holding regions 92. They monitor whether the compensation plate
91 lies on the holding regions or was deflected. Collisions of the
gripper can hereby be detected. The sensors 94 in the embodiment
are inductive sensors. In the embodiment, in this respect, a
plurality of sensors are provided so that information can be
obtained on the direction of the deflection of the compensation
plate 91. Four sensors are in particular provided in this
respect.
[0192] The data obtained from the sensors can in this respect be
used for controlling the gripper as follows: In normal operation,
the compensation unit does not deflect so that the gripper adopts a
defined position with respect to the gripping arm which remains
unaffected by the compensation unit. On a collision, the
compensation unit, however, deflects, which is recognized by the
sensors 94.
[0193] In this case, the control still allows a certain adjustment
path of the gripping arm which is, however, smaller than the
compensation path of the compensation unit.
[0194] If the movement of the gripping arm, however, exceeds this
permitted adjustment path after the recognition of a collision, the
picking procedure is stopped and the gripper is traveled back into
a zero position. A picking procedure is thereupon started again in
that the workpieces are first detected and then a new picking
movement is initiated. The compensation unit in this respect
protects against an emergency stop of the robot, which could only
be cancelled again manually.
[0195] In FIGS. 20 to 22, a second embodiment of a compensation
unit in accordance with the invention is shown. This compensation
unit combines a compensation unit with a spherical operation as is
shown in FIGS. 18 and 19 with a compensation unit with a linear
operation in order thus to increase the compensation path.
[0196] The total compensation unit 200 in this respect first
comprises the spherical compensation part 201 which substantially
corresponds in design to the first embodiment of a compensation
unit and combines it in series with a second compensation part 202
which has a linear operation.
[0197] As can in particular be recognized well in FIG. 21, the
spherically operating compensation part 201 has the same mechanical
design as the first embodiment of a compensation unit in accordance
with the invention, with the same reference numerals also being
used for this purpose. In this respect, a base element 90 is in
particular provided at which the compensation plate 91 is arranged
and is engaged around by holding elements 92 of the base element
90. A spring arrangement 93 which presses the compensation plate 91
toward the holding regions 92 is arranged between the base element
90 and the compensation plate 91. In this respect, adjustment
elements 97 are shown via which the preload of the spring
arrangement 93 can be changed.
[0198] The design of the spherically operating compensation part
201 differs from the first embodiment of a compensation unit in
accordance with the invention only with respect to the sensor which
is used for detecting a compensation movement. Unlike in the first
embodiment, in this respect a light barrier is used having a
transmitter 99a and a receiver 99b whose light path runs through a
bore 98 through the compensation plate 91. If the compensation
plate 91 is deflected in this respect, it interrupts the light path
of the light barrier.
[0199] The sensor thus recognizes in accordance with the invention
the compensation movement of the spherically operating compensation
part 201. No sensor is in contrast provided for the linearly
operating compensation part 202.
[0200] The linearly operating compensation part 202 is in this
respect arranged between the base element 90 and the gripping arm.
In this respect, fastening regions 203 at which bars 204 are
arranged are provided in the corner regions of the base element 90.
The bars 204 are guided in a linearly displaceable manner in guides
205 which are arranged at a plate 210. The plate 210 is then in
turn connected to the end of the gripping arm. The movement of the
bars 204 in the guides 205 takes place against the preload of a
spring arrangement 206 which can be set via adjustment elements
207.
[0201] The two-stage compensation unit in accordance with the
present invention is combined in the embodiment with a magnetic
gripper 211 and can be coupled via a cropped gripping arm extension
212 to a gripping arm, in particular to a robot arm. For this
purpose, the gripping arm extension 212 has a coupling surface 213
with which it can be coupled to the last pivot joint of a robot
arm.
[0202] The two compensation parts 201 and 202 of the compensation
unit are configured in this respect such that the spherically
operating compensation unit 201 deflects first and only then the
linearly operating compensation unit 202. The linearly working
compensation unit 202 can in this respect have a compensation path
between 1.5 and 5 cm, preferably between 2 and 3 cm. This
compensation path allows the movement of the gripper to be braked
in good time in the event of a collision before the total
compensation path of the compensation unit has been utilized.
[0203] The preload of the spring units of the second embodiment of
a compensation unit could be set in the same manner as the spring
load in the first embodiment of a compensation element in
accordance with the invention. In this respect, the preload of the
spring unit 93 could in particular be set so that it also takes up
the static loads from the griper and a workpiece hung on with a
gripper pivoted to the side by 90.degree. without deflecting the
compensation unit. The preload of the spring unit 206 of the linear
part of the compensation unit were then be set correspondingly
greater. In this respect, however, it must be taken into account
that the preloads of the two parts of the compensation unit have to
be set so that the compensation units still deflect beneath the
maximum load limit of the robot arm. This is in particular
difficult to realize with very heavy grippers or very heavy
workpieces in which the static load already lies close to the
maximum load of the gripping arm.
[0204] Alternatively, the preload of the spherical part of the
compensation unit can therefore be set such that it only takes up
the static load by the magnetic gripper when it is located in a
position directed 90.degree. to the side, but already deflects with
a workpiece hung on in this position.
[0205] The present invention in this respect makes use of the fact
that the gripper with the picked up workpiece can be moved
immediately after the picking up into a travel position in which
the gripping surface faces downward so that the static loads by the
gripper and the workpiece are taken up by the compensation unit
without it being deflected. A slanted orientation of the gripper
is, in contrast, only necessary on the traveling toward the
workpiece to bring the gripping surface of the gripper into
coverage with the main surface or with the engagement points of the
workpiece.
[0206] In this respect, the gripper advantageously travels
perpendicular to the gripping surface toward the workpiece, picks
it and is then traveled back in the opposite direction again
together with the workpiece. In this respect, the signal of the
sensor of the compensation unit is not considered for a certain
path distance on the moving back in order not to evaluate a
deflection of the compensation unit solely due to the static load
by the workpiece hung on and/or due to dynamic loads due to the
traveling of the gripping arm erroneously as a collision. During
this path distance, the gripper is simultaneously traveled into a
travel position in which the gripping surface and thus the tool
face vertically downwardly and thus do not act against the spring
elements of the compensation unit.
[0207] If the gripper is moved back by a certain distance and if it
was pivoted in the travel position, the signal of the sensor of the
compensation unit is again used to detect collisions of the gripper
or of the workpiece with interference edges.
[0208] On the traveling of the gripper toward a workpiece, the
signal of the sensor of the compensation unit can moreover be
utilized to detect the contact of the gripper with the workpiece.
The gripper is in this respect traveled slowly to the workpiece
until the compensation unit deflects.
[0209] Independently of the exact embodiment of the compensation
unit, in this respect in accordance with the present invention,
work can be carried out with different travel speeds for the
gripping arm depending on the region in which the gripper is
located. The gripping arm can in this respect be moved in fast
motion, i.e. at a high speed, in a region in which the gripper is
located outside the container and thus no collision with
interfering edges is to be feared. If the gripper is, in contrast,
located in the region of the container so that collisions have to
be anticipated, it preferably works at a second, lower speed. The
speed is in this respect selected so that the gripper can be
stopped on a collision with an interference edge before the
compensation path of the compensation unit is completely used up
and the compensation unit does not permit any further compensation
movement. In the near region to the workpiece to be picked up, the
gripper is furthermore preferably traveled at a third, even lower
speed. This still allows a certain travel path of the gripper or
gripping arm on the detection of a collision before its movement
has to be stopped.
[0210] Embodiments of the methods in accordance with the present
invention will now be presented in more detail again with reference
to flowcharts. They can preferably be carried out using apparatus
such as were described above.
[0211] FIG. 32 in this respect shows the routine of the detection
of the workpieces in an embodiment of the present invention, and
indeed both for the case that workpieces randomly arranged in a
container are detected and workpieces randomly arranged on an
intermediate station are detected.
[0212] In step 100, the system is located in a starting state. The
gripper for picking the workpieces can in particular be arranged
outside the detection region in this starting state. The gripper
can for this purpose either be set down in a parking position or
can carry out actions in a region outside the detection region such
as, for example, placing down an already picked workpiece.
[0213] In step 101 or 106, a measurement now takes place by the
sensors of the object recognition device. For this purpose, in
particular a 3D laser scanner can be used in the embodiment. With
the 3D laser scanner used in the embodiment for detecting the
workpieces in the container, the 3D laser scanner is first traveled
into a measuring position above the container from where the
scanner is pivoted over the detection region. Alternatively, a
detection during the horizontal travel movement of the 3D laser
scanner would also be possible. On the detection of the workpieces
on the intermediate station in accordance with step 106, the sensor
is, in contrast, fixedly installed, with it being pivoted by
pivoting over the detection region.
[0214] Alternatively to the use of a 3D laser scanner, a camera
system or a combination of a camera system and a laser scanner
could also be used. A 2D or 2.5D detection by means of a camera can
in particular also be considered in this respect.
[0215] In step 102, the data are now evaluated and the workpieces
identified.
[0216] The identified workpieces are evaluated with regard to their
positions toward one another. It is in particular determined in
this respect which workpieces lie highest and which workpieces are
at least partly covered by other workpieces. A selection is hereby
prepared for the decision which part is suitable for picking
[0217] In step 103, a decision is now made as to which part is to
be picked in the next step. If this is not possible using the
existing data, a detection can be carried out again in a new cycle,
for which purpose the system moves back into the starting state in
step 107.
[0218] If, in contrast, a workpiece was selected, a track planning
for the gripper takes place in step 104. The determined parameters
of the part to be picked which describe the position and spatial
arrangement of the part are used as the basis for the track
planning The system in this respect knows its current location and
the target coordinates. The path, the so-called track, can then be
calculated with the aid of the determined spatial data.
[0219] In this respect, a collision identification also
advantageously takes place in which the gripper and the container
are represented by geometrical data and the planned track is
simulated in order thus to determine possible collisions in advance
and to preclude them in the track planning by determining an
alternative path.
[0220] In step 105, the controlling of the gripper and the picking
of a workpiece take place using the data thus calculated.
[0221] Before now the different picking strategies in accordance
with the invention are shown next to one another with reference to
FIGS. 24 and 25, the possibilities for the design of an apparatus
in accordance with the invention should be shown again in overview
by which the corresponding strategies can be implemented.
[0222] An apparatus in accordance with the present invention can
comprise two grippers. A first gripper is used to roughly pick the
parts from the bin. A second gripper is provided for the precise
picking and singularization on an intermediate station which can in
particular be equipped with a transport belt. The second gripper
places the workpieces on a further intermediate station or on a
target receiver for a measurement treatment or work treatment of
the workpieces. Which type of gripper is use depends on the
geometry, the design, the size and/or the weight of the workpieces
to be picked and/or on the number of gripping zones and on the
geometry and the design of the gripping zone.
[0223] The workpieces can, however, possibly catch with one
another, lie above one another or also remain stuck. They can have
gripping zones which are not sufficient for a direct picking from
the bin since they are not sufficiently accessible in certain
positions which they can adopt with a plurality of parts in the
bin. If the parts in this respect possibly only have a specific
gripping zone, a targeted, direct picking with a mechanical gripper
proves not to be sufficiently reliable and is moreover slow and
prone to problems.
[0224] In a preferred case, the first gripper is therefore a
magnetic gripper and the second gripper is a mechanical
gripper.
[0225] The use of a magnetic gripper for the pick in the bin or the
container has the advantage that no exact picking in a precise
gripping zone is required. Furthermore, with a magnetic gripper, a
picking at different gripping points of a workpiece is usually
possible. A picking at the highest point of the workpiece is also
in particular usually possible. Furthermore, with a magnetic
gripper, a simultaneous picking of a plurality of parts is possible
to place them on the intermediate station. In accordance with the
invention, a fast and one hundred percent emptying of the bin is
thus possible by the use of a magnetic gripper.
[0226] A mechanical gripper has the advantage that the part can be
picked precisely in a gripping zone so that the workpiece can
subsequently be placed individually in a defined position on or in
a receiving station. The receiving station can in this respect be
the receiving station of a further intermediate station or the
target receiver of a measurement station or processing station. The
workpiece can equally be placed on an intermediate station which
serves as a buffer station or as a demagnetization station or
measurement station.
[0227] The preferred case of a combination of a magnetic first
gripper and a mechanical second gripper is in particular used with
workpieces having a position-orientated gripping zone and/or an
asymmetrical, symmetrical or rotationally symmetrical contour with
a corresponding size and weight. A magnetic gripper can in this
respect naturally only be used when the workpiece can be picked by
a magnetic gripper, that is comprises metal, for example.
[0228] In this respect, the magnetic gripper places the workpieces
on an intermediate station, where they are detected again so that
they can now be picked directly by the mechanical gripper and can
then be placed onto a processing station, measurement device or a
transport belt.
[0229] The following further combinations for the configuration of
the first and second grippers are likewise conceivable:
mechanical/mechanical, pneumatic/mechanical, mechanical/pneumatic,
pneumatic/pneumatic and magnetic/pneumatic. Any desired other
combinations of mechanical and/or pneumatic and/or magnetic
grippers are also conceivable.
[0230] The grippers can in this respect each be moved either by a
robot arm or a linear portal or a surface portal. Optionally, the
respective grippers can be combined with a compensation unit and/or
with a force torque sensor depending on which strategies are to be
used in picking The compensation unit in this respect improves the
system security in that it prevents the necessity of an operator
intervention on collisions.
[0231] The intermediate station has a transport belt which
transports the workpieces from the placing region into a removal
region. In this respect, the placed down parts are conveyed via a
workpiece slide to the transport belt. So that the parts placed
down by the magnetic gripper come to lie as ideally as possible on
the transport belt, the transport belt is bounded by slanted metal
sheets which allow workpieces sliding onto the margin of the
transport belt to slide back onto the belt. At the same time, a
flap which can be moved by the workpieces, in particular a
pivotable metal sheet or a transverse bar, can be installed above
the transport belt so that parts lying above one another can still
be singularized or parts not positioned correctly tilt over. The
workpieces can hereby be better detected by the scanner or camera
and can be picked better.
[0232] A design with only one gripper which picks first in the
container, places the workpiece on an intermediate station and then
picks the workpiece again for singularization would be
alternatively conceivable. The first gripper would thus also be
used for removing the workpiece from the intermediate station and
for placing it on a further intermediate station or the target
receiver.
[0233] The invention in this respect comprises the following
methods which can in particular be carried out in the operation of
an apparatus in accordance with the invention: Sorting out
workpieces:
[0234] If the first gripper is combined with a force tongue sensor,
a selection can already be carried out at this point by weight of
the workpieces. Workpieces which lie outside a specific limit with
respect to weight can in particular be sorted out. They can in
particular be sorted out into a sorting out container.
[0235] A sorting out by the first gripper is also possible in that
workpieces which are recognized as lying outside a predefined
specification on detection are picked up and are placed in a
sorting out container instead of on the intermediate station.
[0236] Workpieces which are detected on the intermediate station
and which lie outside a predefined specification can be sorted out.
This can in particular take place by a further transport of such
workpieces into a sorting out container at the end of the transport
belt.
[0237] It is equally conceivable to hold a just picked part at a
measurement device where e.g. geometries, surfaces (for example a
lacquering) and/or markings (e.g. by codes) can be measured and/or
inspected. If this measurement indicates that a part lies within a
predefined specification, the picked part is placed down normally,
e.g. on the intermediate station or on a target receiver. If it is
outside the specification, it is sorted out.
[0238] Prevention of system stops:
[0239] A system stop can be prevented by picking with an offset at
which the gripper slightly misses the ideal picking position. In
this case, the gripper travels back around 25 mm and starts to
travel again in order to pick more precisely this time.
[0240] Furthermore, it can be recognized via a force torque sensor
when too many parts were picked at once. In particular when hereby
the maximum load of the robot could be exceeded, the load can be
reduced by a dropping of the workpieces back into the container.
The parts remaining at the gripper can then be unloaded at the
intermediate station.
[0241] If the situation arises at the intermediate station that the
object recognition device cannot detect the part exactly since the
parts e.g. lie above one another and cannot be detected exactly or
that a picking is not possible or only takes place with
insufficient accuracy, the following strategies can be used:
[0242] On the one hand, a further, lower-lying transport belt can
be used on which the parts not picked travel on in order thus to
adopt the required position by falling over a stage. The workpiece
thus has a second chance and is again supplied to the transport
belt for precise picking (Loop 2). In this respect, e.g. with
smaller parts which can catch with one another, provision can also
be made that the transport path guided as a circuit has
singularization devices which pulls the parts apart and hereby
singularizes them. For this purpose, sheet metals or transverse
bars can, for example, be used which narrow the transport belt
and/or brush the workpieces.
[0243] If the parts are admittedly picked, but no exact picking
takes place, this can be registered via a sensor. For this purpose,
for example, a pneumatic cylinder can be provided at the mechanical
gripper. This not only recognizes the gripping position within a
necessary limit for a subsequently precise placing of the parts,
but also has the consequence of a stabilization of the part in
picking On a recognized inexact picking, the second gripper can
place the workpiece back onto a front part of the transport belt of
the intermediate station. The part thus also has a second chance
for exact picking (Loop 1).
[0244] On picking a workpiece from a container, the above-named
strategies can in particular be combined to form the routine shown
in FIG. 24:
[0245] In this respect, the system is in a base state in step 110
in which the track calculated by the track planning is predefined
for the gripper. In step 111, the attempt of picking then takes
place using the calculated track planning
[0246] If in step 112 more than one workpiece is picked, the
further procedure depends on whether this can be recognized by a
sensor. If this is not the case, the workpieces are simply unloaded
onto the transport belt. Otherwise it is possible to carry out a
measurement with respect to force, weight, number or optics in step
113. A force torque sensor can in particular be used in this
respect. Alternatively, a 3D laser or a 2D camera or a 2.5D camera
can also be used here. A decision now takes place by recognizing
predefined limits whether too many parts were picked up. If too
many parts were picked up, a falling of all parts back into the bin
can take place either in step 114 by a switching off or reducing of
the gripping force of the gripper. After this step 115, a
completely new picking procedure takes place, including detection
of the parts. Alternatively, in step 117, a part regulation can
take place by partial reduction of the force of the gripper and
thus partial dropping of the workpieces back into the bin. In step
119, a check can again be made whether at least one part is hanging
on. If such a part is hanging on, this can be unloaded on the
intermediate station in step 120. If no part is hanging on, a new
picking cycle can be started directly.
[0247] If, in contrast, it is recognized in the measurement that
only one part is hanging on, this can be unloaded directly. If it
is recognized in the measurement that no part at all was picked up,
a new picking cycle can start immediately.
[0248] It is shown in step 122 how it is possible to proceed if a
centered picking is not possible. In this case, the gripper either
searches for the highest point of the selected part and grips at
this point again in step 124 or it picks with an offset in step
123, i.e. it travels back by about 25 mm from the part and then
travels toward the part again.
[0249] Alternatively, such a decision can already take place when
it is recognized in the selection of the workpiece to be picked
that none of the parts is centered in a pickable manner. In this
case, a picking can already be planned in the track planning with
an offset at which the gripping surface and the main surface of the
workpiece do not fully overlap or a picking at the highest point
can be planned.
[0250] The system can deal with collisions as follows in this
respect: If no collision occurs, as in step 121, the workpieces can
thus be unloaded on the intermediate station. If, in contrast, in
step 125, a collision is recognized, for example, by a force torque
sensor and/or a compensation unit, the control still allows a
defined travel path. If this is also exceeded, the picking
procedure is stopped and the system starts a new picking cycle. If,
in contrast, the collision in step 127 is only recognized by the
emergency stop function of the robot, this results in a system stop
in step 128 which can only be cancelled again by an operator
intervention 129.
[0251] On the picking of a workpiece from the intermediate station,
and in particular from the transport belt of the intermediate
station, the strategies in accordance with the invention can in
particular be combined to form the routine shown in FIG. 25:
[0252] First, in steps 130, a workpiece travels on the transport
belt into the recognition region of the object recognition device
and the transport belt stops. Then the recognition is carried out,
in particular a scanning by a 3D laser scanner. It can be pivotable
or travelable in a vertical or horizontal manner or can be arranged
at a fixed position above the transport belt. Alternatively, a
taking of an image can take place via a 2D, 2.5D or 3D camera.
After the evaluation of the data and the corresponding
determination of a track for the gripper, as was already previously
described, the picking then takes place in step 131.
[0253] The picking of more than one part in step 138 can trigger
the same procedure as in the picking from a container. If in this
respect a mechanical gripper is used, only the possibility remains,
however, of dropping all parts in steps 140 and 141.
[0254] The procedure in the event of a collision in steps 148 or
144 is also identical to the procedure on picking from a
container.
[0255] On an inexact picking in step 143, a procedure can likewise
be following as was presented with respect to the corresponding
steps in FIG. 23. These strategies can in particular be used when a
magnetic gripper is used as the second gripper.
[0256] Furthermore, when the picking accuracy in step 134 is no
longer sufficient, the part can again be placed onto the front part
of the transport belt (Loop 1) so that the workpiece can again be
detected and picked.
[0257] If no recognition is possible or if no workpiece can be
picked, the workpiece can again be conveyed over a return path onto
the transport belt in a corresponding embodiment of the
intermediate station so that a repeat chance for picking is given
(Loop 2). Otherwise the workpiece which cannot be picked has to be
traveled into a sorting out container.
[0258] The present invention makes possible a handling of the
workpieces with fast cycle times, small error rates and a great
accuracy in picking with the above-presented apparatus and methods.
In this respect, a high process security results by the avoidance
of system downtimes which would require operator intervention.
Furthermore, the present invention allows a 100 percent emptying of
the containers.
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